Dimmers are generally known and serve to vary electrical power. Power variation using dimmers may be achieved by leading-edge phase control or by trailing-edge phase control. In leading-edge phase control, the current is switched on with delay after the zero crossing of the AC voltage and flows to the next current zero crossing. It is typically used in the case of an inductive load response. In trailing-edge phase control, on the other hand, the current is switched on immediately after the zero crossing and switched off again before the next zero crossing. This is typically used in the case of a capacitive load response. To generate the control commands required therefor for its switching components, the dimmer has a main control device.
Some dimmers are described as “multichannel dimmers”. These have a plurality of individual dimmers, which each control part of the electrical load. To increase power, these “dimmer channels” are connectable on the output side in parallel, sequentially or in a mixture of ways. A plurality of physical channels are interconnected and a powerful logical channel is obtained. The dimmer channels may here be in one device or indeed in a plurality of devices.
It is important, however, because of this interconnection, that the outputs of the dimmer channels are largely synchronized. If, for example, two channels were connected in parallel and the second channel switches too late (leading-edge phase) or too early (trailing-edge phase), the first channel is overloaded to a greater extent than if both switch incorrectly but synchronously. This may lead to overheating or to failure of the first dimmer channel, or even to disconnection of the dimmer.
In known multichannel dimmers, each dimmer channel has its own channel control device, e.g. a processor, and a measurement device for measuring the electricity in the channel, which may sometimes also be formed by this processor. Using the measurement device, the channel control device receives the information about the periodic behavior of the electricity in the channel which is needed to identify the leading-edge phase or the trailing-edge phase. The control commands generated by the main control device are transmitted in each case via a communication link to the channel control devices of the dimmer channels and there implemented in accordance with the information about the periodic behavior of the electricity in the channel.
The complexity of the measurement devices in particular leads to high development and production costs. Inaccuracies in zero crossing identification may also arise as a result of component tolerances or due to component aging. The resultant time differences then lead to non-synchronous switching of the dimmer channels and to the above-described problems. Device replacement or recalibration of the components thereof is possible, but not without cost and optionally consequential damage due to malfunctioning.
German patent DE102017213888B3 describes a dimmer for controlling the power consumption of a connectable load, having at least two dimmer channels, wherein at least one dimmer channel is configured as a measurement dimmer channel for identifying the behavior of the electricity. To synchronize the dimmer channels, starting from the measurement dimmer channel a channel communication link leads in each case from one dimmer channel to the next dimmer channel.
German patent DE102016209278B3 describes a dimmer system for controlling the power consumption of a connectable load and a method for controlling the power consumption of a connectable load in a dimmer system, having a master control device and at least two slave dimmers, wherein the master control device outputs synchronization signals for synchronizing the respective outputs of the slave dimmers via a suitable communication link to the respective slave dimmers, and wherein the slave dimmers are connected in parallel in order to provide a jointly controlled output for the connectable load.